To determine the potential benefits of developing irrigation in northern Réunion, the authors used a sugarcane growth model to simulate expected yield gains due to irrigation. This study was launched in response to new provisions of the Common Market Organisation for sugar, which will induce a sugar price reduction In Réunion that will become effective in 2013. To ensure the survival of the sugarcane cropping sector, Réunion departmental authorities thus want to pro-mote irrigation in a zone hitherto not irrigated in order to improve its productivity. To carry out this survey, the authors thus implemented three methodologies: GIS, modelling and data processing. One difficulty encountered concerned the spatial representation of discretised parameters such as available soil water and rainfall. This problem was overcome by interpolating the production potentials, i.e. the model outputs and not the elementary parameters (inputs). The main interest of this study was to use sugarcane modelling software (MOSICAS), which is still in the experimental stage, in an operational setting to generate some important results for decision makers. The yield map drawn up on the basis of these results revealed that, in this area, irrigation could provide an average cane yield gain of 54 000 t for an annual production of 285 000 t, so setting up irrigation in this area would be largely warranted. Lastly, MOSICAS software was also found to be of considerable interest for practical applications.